1. Field of the Invention
The present invention relates to an optical information recording and reproducing apparatus which is capable of recording information data on an optical recording medium and reproducing it therefrom.
2. Description of the Related Art
In order to read recorded information with high accuracy from an optical recording medium in which the information is recorded in a high-density state, it is necessary to exclude the influence of crosstalk exerted from tracks contiguous to both sides of a target track to be read.
To remove such crosstalk, in a pickup optical system, a laser beam is divided into three by means of, for example, a grating element so as to generate three laser beams, then irradiating the beams onto the target track and the contiguous tracks, whereby, the recorded information is read from three tracks simultaneously. Thereafter, a crosstalk component that has been superimposed in a readout signal that has been read from the target track is calculated, based on a readout signal that has been read from each of the contiguous tracks. The crosstalk component is then subtracted from the readout signal that has been read from the target track so as to remove the crosstalk.
When, however, the aforementioned optical system is also used to record information data on a target track, such a problem occurs that the laser beam is irradiated onto not only the target track but also contiguous tracks thereto and therefore the already recorded data on the contiguous tracks will be deleted because of the irradiation of the recording spot onto those contiguous tracks.
The present invention has been conceived to solve such a problem as mentioned above, and it aims to provide an optical information recording and reproducing apparatus which is capable of preventing recorded data from being unwontedly deleted within a recording operation mode and is capable of reading information with high accuracy as a result of the removal of crosstalk in the reproduction operation mode.
An optical information recording and reproducing apparatus according to the present invention is an optical information recording and reproducing apparatus for recording information on a recording medium and reproducing the information therefrom by irradiating a beam of light onto the recording medium. The apparatus has a laser generating element that generates a single laser beam and a laser beam irradiating means for, within a reproduction operation mode, dividing the laser beam into a plurality of divided laser beams and irradiating the laser beams individually toward a target track of the recording medium and, within a recording operation mode, reducing the quantity or amount of light of all but one beam of the laser beams in comparison with that one beam and irradiating them all onto the recording medium.